Lubricant pump system and method for aircraft engine

ABSTRACT

Lubricant pump systems and associated methods for aircraft engines are provided. The method includes receiving an input torque, dividing the input torque between a first load path receiving a first portion of the input torque, and a second load path receiving a second portion of the input torque. A first lubricant pump of the aircraft engine is driven via the first load path using the first portion of the input torque. A second lubricant pump of the aircraft engine is driven via the second load path using the second portion of the input torque. When a malfunction of the second lubricant pump occurs, the method includes ceasing to drive the first lubricant pump and the second lubricant pump using the input torque.

TECHNICAL FIELD

The disclosure relates generally to aircraft engines, and moreparticularly to lubrication systems of aircraft engines.

BACKGROUND

A typical aircraft engine has a lubrication system to meet thelubrication and cooling needs of various components of the engine. Thelubrication system can deliver oil from an oil tank to the variouscomponents within the engine, recover the used oil from the components,and return the recovered used oil back to the oil tank forrecirculation. The arrangement of the pumps of the lubrication system ofan aircraft engine can be bulky and require complex and/or cumbersomeplumbing. Improvement is desirable.

SUMMARY

In one aspect, the disclosure describes a lubricant pump system for anaircraft engine. The lubricant pump system comprises:

a source of motive power;

a first lubricant pump drivingly connected to the source of motive powervia a first load path receiving a first portion of the motive power;

a second lubricant pump drivingly connected to the source of motivepower via a second load path receiving a second portion of the motivepower, the second load path being separate from the first load path, thesecond portion of the motive power being different from the firstportion of the motive power; and

a mechanical fuse operatively disposed between the source of motivepower and the first load path, the mechanical fuse also beingoperatively disposed between the source of motive power and the secondload path.

In another aspect, the disclosure describes a method of drivinglubricant pumps of an aircraft engine. The method comprises:

receiving an input torque;

dividing the input torque between a first load path receiving a firstportion of the input torque, and a second load path receiving a secondportion of the input torque;

driving a first lubricant pump of the aircraft engine via the first loadpath using the first portion of the input torque;

driving a second lubricant pump of the aircraft engine via the secondload path using the second portion of the input torque; and

when a malfunction of the second lubricant pump occurs, ceasing to drivethe first lubricant pump and the second lubricant pump using the inputtorque.

In a further aspect, the disclosure describes an aircraft enginecomprising:

a lubrication load;

a supply pump operatively connected to deliver lubricant to thelubrication load;

a scavenge pump operatively connected to recover the lubricant from thelubrication load;

a first drivetrain defining a first load path between a source of motivepower and the supply pump, the first drivetrain being drivinglyconnected to the source of motive power via a frangible connection; and

a second drivetrain defining a second load path between the source ofmotive power and the scavenge pump, the second load path being separatefrom the first load path, the second drivetrain being drivinglyconnected to the source of motive power via the frangible connection.

Further details of these and other aspects of the subject matter of thisapplication will be apparent from the detailed description includedbelow and the drawings.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings, in which:

FIG. 1 shows a schematic axial cross-section view of an exemplaryaircraft engine including a lubricant pump system as described herein;

FIG. 2 is a schematic representation of an exemplary lubricant pumpsystem of the aircraft engine of FIG. 1 ;

FIG. 3 is a schematic representation of another exemplary lubricant pumpsystem of the aircraft engine of FIG. 1 ; and

FIG. 4 is a flow diagram of a method of driving lubricant pumps of anaircraft engine.

DETAILED DESCRIPTION

The following disclosure describes lubrication systems of aircraftengines and methods of operating such lubrication systems. In someembodiments, the systems and methods described herein may promote safeutilization an efficient packaging (i.e., use of space) of lubricantpumps associated with an aircraft engine. In some embodiments, thesystems and methods described herein may promote simplified plumbing by,for example, segregating lubricant supply lines of supply pumps fromlubricant return lines of scavenge pumps. In some embodiments, thesystems and methods described herein may be configured to, as afail-safe, automatically stop one or more supply pumps in the event of amalfunction of one or more scavenge pumps. This may cause lubricantsupply to a lubrication load from which the lubricant is no longer beingrecovered to be reduced or stopped. In some situations, this maypotentially impede an escalation of the malfunction by stoppingflammable lubricant from being supplied to a region of the aircraftengine potentially prone to cause ignition of the lubricant for example.

The terms “engaged”, “connected” or “coupled” may include both directengagement, connection or coupling (in which two elements contact eachother) and indirect engagement, connection or coupling (in which atleast one additional element is located between the two elements).

The term “substantially” as used herein may be applied to modify anyquantitative representation which could permissibly vary withoutresulting in a change in the basic function to which it is related.

Aspects of various embodiments are described through reference to thedrawings.

FIG. 1 shows a schematic representation of aircraft engine 10 (referredhereinafter as “engine 10”). Engine 10 is illustrated as a turbofan gasturbine engine as an example. However, it is understood that the systemsand methods described herein are also applicable to other types ofaircraft engines such as turboshaft and turboprop gas turbine enginesfor fixed-wing and/or rotary wing aircraft applications for example.Engine 10 may suitable for use in (e.g., subsonic flight) aircraftapplications. Engine 10 may include, in serial flow communication, fan12 through which ambient air is propelled, multistage compressor 14 forpressurizing the air, combustor 16 in which the compressed air is mixedwith fuel and ignited for generating an annular stream of hot combustiongases, and turbine section 18 for extracting energy from the combustiongases.

Engine 10 may include lubricant pump system 20 (referred hereinafter as“system 20”), which may be part of a lubrication system of engine 10 forservicing one or more lubrication loads 22 (referred hereinafter in thesingular) of engine 10. Lubrication load 22 may include one or morebearings and/or gears that require lubrication and/or cooling. System 20may include lubricant tank 24 and one or more supply pressure lubricantpumps 26 (referred hereinafter in as “supply pump(s) 26”) in fluidcommunication with lubricant tank 24. Supply pump(s) 26 may beoperatively connected to supply lubricant (e.g., lubricating fluid, oil)from lubricant tank 24 to lubrication load 22 of engine 10.

System 20 may include one or more scavenge lubricant pumps 28 (referredhereinafter as “scavenge pump(s) 28”) that may drive (i.e., recover)used lubricant collected in one or more sumps of engine 10 back tolubricant tank 24 for recirculation. It is understood that someembodiments of system 20 may include additional components than thoseillustrated herein. Supply pump(s) 26 and scavenge pump(s) 28 mayinclude gear type, gear-rotor type or other suitable type of pumps.

Supply pump(s) 26 and scavenge pump(s) 28 may be driven by any suitablesource of motive power available such as electric motor(s), hydraulicmotor(s), pneumatic motor(s) and/or one or more rotating/driven shaftsof engine 10 being drivingly connected to supply pump(s) 26 and/or toscavenge pump(s) 28 via accessory gearbox 30 (referred hereinafter as“AGB 30”) for example. In some embodiments as shown in FIG. 1 , a singleoutput (output pad) of AGB 30 may be used as a source of motive power(e.g., an input torque) to drive supply pump(s) 26 and scavenge pump(s)28.

In some embodiments of system 20, supply pump(s) 26 and scavenge pump(s)28 may be driven by AGB 30 via separate respective drivetrains 32A, 32Bdefining separate load paths. First drivetrain 32A and second drivetrain32B may each include one or more shafts, gear(s), coupling(s), link(s),joint(s) and/or other components suitable for transferring (e.g.,rotational) motive power. First drivetrain 32A may define a first loadpath receiving a first portion of the motive power from AGB 30 fordriving supply pump(s) 26, and second drivetrain 32B may define a secondload path receiving a second portion of the motive power for drivingscavenge pump(s) 28. In other words, the motive power transferred tosystem 20 from AGB 30 may be divided (i.e., split) between the firstload path defined by first drivetrain 32A and the second load pathdefined by second drivetrain 32B. The first load path defined by firstdrivetrain 32A, and the second load path defined by second drivetrain32B may be separate from each other. The first portion of motive powertransferred to the first load path may be different from the secondportion of motive power transferred to the second load path. In otherwords, first drivetrain 32A and second drivetrain 32B may be configuredas separate branches that drive different pumps (e.g., pump stacks)using different portions of the motive power input into system 20 fromAGB 30 or otherwise.

The input motive power or input torque received at system 20 may bereceived via a suitable mechanical fuse 34 (referred hereinafter as“fuse 34”) operatively disposed between the source of motive power andboth the first and second load paths defined by first drivetrain 32A andsecond drivetrain 32B. Both first drivetrain 32A and second drivetrain32B may be drivingly connected to the source of motive power via asingle common fuse 34 so that an obstruction in first drivetrain 32A orin second drivetrain 32B may cause fuse 34 to break and simultaneouslycause first drivetrain 32A and second drivetrain 32B to become drivinglydisconnected from the source of motive power. Consequently, in the eventof a malfunction of scavenge pump(s) 28, such as scavenge pump(s) 28becoming seized or exhibiting an increased resistance to being drivenvia second drivetrain 32B, the breaking of fuse 34 would cause thedriving of scavenge pump(s) 28 and of supply pump(s) 26 to cease.Similarly, in the event of a malfunction of supply pump(s) 26, such assupply pump(s) 26 becoming seized or exhibiting an increased resistanceto being driven via first drivetrain 32A, the breaking of fuse 34 wouldcause the driving of scavenge pump(s) 28 and of supply pump(s) 26 tocease.

Fuse 34 may include any suitable frangible connection(s) suitable fortransmitting motive power during normal operation of scavenge pump(s) 28and supply pump(s) 26, and may be configured (e.g., designed, sized) tobreak/fail in the event of the motive power or torque being transferredexceeding a threshold indicative of a malfunction in first drivetrain32A and/or in second drivetrain 32B. Fuse 34 may be of a type known as a“torque fuse”. For example, fuse 34 may be sized to break/fail in theevent of a malfunction of a single scavenge pump 28 or of a singlesupply pump 26. Fuse 34 may be a mechanical sacrificial part designed tobreak in the event of a malfunction that increases the resistance torotational movement transferred to first drivetrain 32A and/or to seconddrivetrain 32B. In various embodiments, fuse 34 may include a shear pin,a shear neck, and/or a (e.g., Woodruff) key for example.

FIG. 2 is a schematic representation of another exemplary lubricant pumpsystem 120 (referred hereinafter as “system 120”) that may be part of alubrication system of engine 10. Aspects of system 120 may be combinedwith other systems described herein. System 120 may include componentsof system 20 described above and like elements have been identifiedusing reference numerals that have been incremented by 100.

Input torque T may be received from AGB 30 or other source of motivepower and may be divided between the first load path defined by firstdrivetrain 132A and the second load path defined by second drivetrain132B. Input torque T may be received and transferred to first drivetrain132A and to second drivetrain 132B via fuse 134. Input torque T may besplit into first torque portion TA delivered to first drivetrain 132A,and second torque portion TB delivered to second drivetrain 132B. Firstdrivetrain 132A may be used to drive one or more supply pumps 126A andoptionally one or more scavenge pumps 128A. Second drivetrain 132B maybe used to drive one or more scavenge pumps 128B and optionally one ormore supply pumps 126B. In various embodiments, first drivetrain 132Amay be used to drive supply pump(s) 126A exclusively, or may be used todrive a combination of supply pump(s) 126A and scavenge pump(s) 128A.Similarly, in various embodiments, second drivetrain 132B may be used todrive scavenge pump(s) 128B exclusively, or may be used to drive acombination of scavenge pump(s) 128B and supply pump(s) 126B. In someembodiments, the pumps driven by first drivetrain 132A may be arrangedserially along the first load path. In some embodiments, the pumpsdriven by second drivetrain 132B may be arranged serially along thesecond load path.

In some embodiments, input torque T may be transferred to firstdrivetrain 132A and second drivetrain 132B via coupler 136. Coupler 136may include any suitable structure suitable to transfer motive power(e.g., input torque T) to both first drivetrain 132A and seconddrivetrain 132B. In other words, coupler 136 may serve to drivinglycouple first drivetrain 132A and second drivetrain 132B to input torqueT. In some embodiments, coupler 136 may include a suitable torquesplitter capable of dividing input torque T into first torque portion TAdelivered to first drivetrain 132A and second torque portion TBdelivered to second drivetrain 132B. In some embodiments, coupler 136may include a torque dividing gearbox having an input and two outputsfor respectively driving first drivetrain 132A and second drivetrain132B. In various embodiments, first torque portion TA delivered to firstdrivetrain 132A and second torque portion TB delivered to seconddrivetrain 132B may be substantially equal or may be different dependingon the configuration of coupler 136 and on the number and type(s) ofpumps that are driven by each of first drivetrain 132A and seconddrivetrain 132B. In some embodiments, coupler 136 may be configured ascoupler 236 shown in FIG. 3 and described below.

Even though system 120 of FIG. 2 only shows two drivetrains respectivelydriving two pump stacks, it is understood that system 120 could includeone or more additional drivetrains that are used to drive one or moreadditional pump stacks via fuse 134 using input torque T. In otherwords, input torque T and fuse 134 could be used to drive two or moredrivetrains each driving one or more lubricant (e.g., supply and/orscavenge) pumps.

FIG. 3 is a schematic representation of another exemplary lubricant pumpsystem 220 (referred hereinafter as “system 220”) that may be part of alubrication system of engine 10. Aspects of system 220 may be combinedwith other systems described herein. System 220 may include componentsof systems 20 and 120 described above. Like elements from system 120have been identified using reference numerals that have been incrementedby 100.

In some embodiments of system 220, the source of motive power mayinclude drive gear 238, which may include an external toothed facereceiving input torque T. Input torque T may be delivered to drive gear238 from AGB 30 (shown in FIG. 1 ) or from another source of motivepower and may be divided between the first load path defined by firstdrivetrain 232A and the second load path defined by second drivetrain232B.

Input torque T may be transferred from drive gear 238 to firstdrivetrain 232A and to second drivetrain 232B via fuse 234. Input torqueT may be split into first torque portion TA delivered to firstdrivetrain 232A and second torque portion TB delivered to seconddrivetrain 232B. First drivetrain 132A may be used to drive one or moresupply pumps 226A and/or one or more scavenge pumps 228A. Seconddrivetrain 232B may be used to drive one or more scavenge pumps 228Band/or one or more supply pumps 226B.

Drive gear 238 may be rotatable about rotation axis RA. Drive gear 238may be rotatably supported by a suitable structure of engine 10 via oneor more bearings 240. In some embodiments, input torque T may betransferred to first drivetrain 232A and to second drivetrain 232B viacoupler 236. Drive gear 238 may have a through central bore 242extending along rotation axis RA. Central bore 242 may have firstopening 244A, and second opening 244B axially opposite first opening244A. The first load path defined by first drivetrain 232A may extendthrough first opening 244A of central bore 242 of drive gear 238. Forexample, first shaft 246A of first drivetrain 232A may extend intocentral bore 242 via first opening 244A and may be drivingly connectedto coupler 236. Similarly, the second load path defined by seconddrivetrain 232B may extend through second opening 244B of central bore242 of drive gear 238. For example, second shaft 246B of seconddrivetrain 232B may extend into central bore 242 via second opening 244Band may be drivingly connected to coupler 236.

Coupler 236 may be disposed inside central bore 242 of drive gear 238.In some embodiments, an axial position of coupler 236 relative torotation axis RA may axially overlap an axial position of one or morebearings 240. In some embodiments, coupler 236 may have an annular(e.g., sleeve) configuration. For example, a radially-outer portion ofcoupler 236 may be drivingly connected with a radially-inner portion ofdrive gear 238 via fuse 234. In some embodiments, fuse 234 may define afrangible connection establishing torque transfer between coupler 236and drive gear 238. In some embodiments, fuse 234 may include a Woodruffor other type of key that is engaged with both coupler 236 and withdrive gear 238. Other types of frangible connections may be suitable.

Coupler 236 may be drivingly connected to both first shaft 246A andsecond shaft 246B. First shaft 246A of first drivetrain 232A may bedrivingly connected to a first radially-inner portion of coupler 236.Second shaft 246B of second drivetrain 232B may be drivingly connectedto a second radially-inner portion of coupler 236. The first and secondradially-inner portions of coupler 236 may be axially-oppositeradially-inner portions of coupler 36. In some embodiments, first shaft246A and second shaft 246B may be drivingly connected to coupler 236 viaone or more splined or other type of connections. The arrangement shownin FIG. 3 may result in the first load path defined by first drivetrain232A, and the second load path defined by second drivetrain 232B beingdrivingly connected to drive gear 238 (and input torque) via the samefuse 234.

In some embodiments of system 220, first shaft 246A and second shaft246B may be drivingly connected via coupler 236 for common rotation. Insome embodiments of system 220, first shaft 246A and second shaft 246Bmay be drivingly connected for common rotation with drive gear 238. Insome embodiments of system 220, first shaft 246A, second shaft 246B,coupler 236, fuse 234 and drive gear 238 may be drivingly connected forcommon rotation. In some embodiments, first shaft 246A may be coaxialwith second shaft 246B. In some embodiments, first shaft 246A and secondshaft 246B may be coaxial with drive gear 238.

FIG. 4 is a flow diagram of a method 1000 of driving lubricant pumps ofengine 10 or of another aircraft engine. Aspects of method 1000 may becombined with other aspects or actions disclosed herein. Aspects ofsystems 20, 120 and 220 may be incorporated into method 1000. In variousembodiments, method 1000 may include:

receiving an input torque T (see block 1002);

dividing input torque T between a first load path receiving first torqueportion TA of input torque T, and a second load path receiving secondtorque portion TB of input torque T (see block 1004);

driving one or more first lubricant pumps of supply pump(s) 26 and/orscavenge pump(s) 28 via the first load path using first torque portionTA (see block 1006);

driving one or more second lubricant pumps of supply pump(s) 26 and/orscavenge pump(s) 28 via the second load path using second torque portionTB (see block 1008); and

when a malfunction of the second lubricant pump(s) occurs, ceasing todrive the first lubricant pump(s) and the second lubricant pump(s) usinginput torque T (see block 1010).

In some embodiments of method 1000, the first lubricant pump may besupply pump 26 and the second lubricant pump may be scavenge pump 28.

Input torque T may be received via fuse 34. Ceasing to drive the firstlubricant pump and the second lubricant pump using input torque T mayinclude causing fuse 34 to break.

In some embodiments, the malfunction of the second lubricant pump mayinclude seizing of the second pump. Ceasing to drive the first lubricantpump and the second lubricant pump using input torque T may includedisconnecting the first load path and the second load path from inputtorque T.

In some embodiments, method 1000 may include substantiallysimultaneously disconnecting the first load path and the second loadpath from input torque T when the malfunction of the second (or first)lubricant pump occurs.

The embodiments described in this document provide non-limiting examplesof possible implementations of the present technology. Upon review ofthe present disclosure, a person of ordinary skill in the art willrecognize that changes may be made to the embodiments described hereinwithout departing from the scope of the present technology. Furthermodifications could be implemented by a person of ordinary skill in theart in view of the present disclosure, which modifications would bewithin the scope of the present technology.

What is claimed is:
 1. A lubricant pump system for an aircraft engine,the lubricant pump system comprising: a source of motive power; a firstlubricant pump drivingly connected to the source of motive power via afirst load path receiving a first portion of the motive power; a secondlubricant pump drivingly connected to the source of motive power via asecond load path receiving a second portion of the motive power, thesecond load path being separate from the first load path, the secondportion of the motive power being different from the first portion ofthe motive power; and a mechanical fuse operatively disposed between thesource of motive power and the first load path, the mechanical fuse alsobeing operatively disposed between the source of motive power and thesecond load path.
 2. The lubricant pump system as defined in claim 1,wherein the first lubricant pump is a supply pump and the secondlubricant pump is a scavenge pump.
 3. The lubricant pump system asdefined in claim 1, wherein the first lubricant pump is one of aplurality of first lubricant pumps drivingly connected to the source ofmotive power via the first load path.
 4. The lubricant pump system asdefined in claim 3, wherein: the second lubricant pump is one of aplurality of second lubricant pumps drivingly connected to the source ofmotive power via the second load path; the first lubricant pumps includesupply pumps; and the second lubricant pumps include scavenge pumps. 5.The lubricant pump system as defined in claim 1, wherein: the source ofmotive power includes a drive gear; the first load path includes a firstshaft drivingly connected to the drive gear via the mechanical fuse; andthe second load path includes a second shaft drivingly connected to thedrive gear via the mechanical fuse.
 6. The lubricant pump system asdefined in claim 5, wherein: the drive gear is rotatable about an axis;the drive gear has a through central bore extending along the axis; thecentral bore has a first opening, and a second opening axially oppositethe first opening; the first load path extends through the first openingof the central bore of the drive gear; and the second load path extendsthrough the second opening of the central bore of the drive gear.
 7. Thelubricant pump system as defined in claim 5, wherein the first shaft andthe second shaft are drivingly connected for common rotation with thedrive gear.
 8. The lubricant pump system as defined in claim 5,comprising a coupler drivingly interconnecting the first shaft and thesecond shaft together, the coupler being drivingly connected to thedrive gear via the mechanical fuse.
 9. The lubricant pump system asdefined in claim 8, wherein: the drive gear is rotatable about an axis;the drive gear has a central bore extending along the axis; and thecoupler is disposed inside the central bore of the drive gear.
 10. Thelubricant pump system as defined in claim 9, wherein: the coupler has anannular configuration; a radially-outer portion of the coupler isdrivingly connected with the drive gear via the mechanical fuse; themechanical fuse includes a frangible connection establishing torquetransfer between the coupler and the drive gear; the first shaft isdrivingly connected with a first radially-inner portion of the coupler;and the second shaft is drivingly connected with a second radially-innerportion of the coupler.
 11. A method of driving lubricant pumps of anaircraft engine, the method comprising: receiving an input torque;dividing the input torque between a first load path receiving a firstportion of the input torque, and a second load path receiving a secondportion of the input torque; driving a first lubricant pump of theaircraft engine via the first load path using the first portion of theinput torque; driving a second lubricant pump of the aircraft engine viathe second load path using the second portion of the input torque; andwhen a malfunction of the second lubricant pump occurs, ceasing to drivethe first lubricant pump and the second lubricant pump using the inputtorque.
 12. The method as defined in claim 11, wherein the firstlubricant pump is a supply pump and the second lubricant pump is ascavenge pump.
 13. The method as defined in claim 11, wherein: the inputtorque is received via a mechanical fuse; and ceasing to drive the firstlubricant pump and the second lubricant pump using the input torqueincludes causing the mechanical fuse to break.
 14. The method as definedin claim 11, wherein: the malfunction of the second lubricant pumpincludes seizing of the second pump; and ceasing to drive the firstlubricant pump and the second lubricant pump using the input torqueincludes disconnecting the first load path and the second load path fromthe input torque.
 15. The method as defined in claim 11, comprisingsubstantially simultaneously disconnecting the first load path and thesecond load path from the input torque when the malfunction of thesecond lubricant pump occurs.
 16. An aircraft engine comprising: alubrication load; a supply pump operatively connected to deliverlubricant to the lubrication load; a scavenge pump operatively connectedto recover the lubricant from the lubrication load; a first drivetraindefining a first load path between a source of motive power and thesupply pump, the first drivetrain being drivingly connected to thesource of motive power via a frangible connection; and a seconddrivetrain defining a second load path between the source of motivepower and the scavenge pump, the second load path being separate fromthe first load path, the second drivetrain being drivingly connected tothe source of motive power via the frangible connection.
 17. Theaircraft engine as defined in claim 16, wherein: the supply pump is oneof a plurality of supply pumps drivingly connected to the source ofmotive power via the first drivetrain; and the scavenge pump is one of aplurality of scavenge pumps drivingly connected to the source of motivepower via the second drivetrain.
 18. The aircraft engine as defined inclaim 17, wherein: the source of motive power includes a drive gear; thefirst drivetrain includes a first shaft drivingly connected to the drivegear via the frangible connection; and the second drivetrain includes asecond shaft drivingly connected to the drive gear via the frangibleconnection.
 19. The aircraft engine as defined in claim 18, comprising acoupler drivingly connecting the first shaft and the second shafttogether, wherein the coupler is drivingly connected to the drive gearvia the frangible connection.
 20. The aircraft engine as defined inclaim 18, wherein: the drive gear is rotatable about an axis; the drivegear has a through central bore extending along the axis; the centralbore has a first opening and a second opening axially opposite the firstopening; the first drivetrain extends through the first opening of thecentral bore of the drive gear; and the second drivetrain extendsthrough the second opening of the central bore of the drive gear.